The invention relates to an apparatus for transporting and stacking of goods, in particular in the form of plates such as metal plates or the like, with a feed transport device which is connected to a stacking device according to the preamble of claim 1.
Furthermore, the invention relates to a process for transporting and stacking goods, in particular in the form of plates such as metal plates or the like, where the current goods are fed by means of a feed transport device with an, in particular, adjustable feed rate, according to the preamble of claim [sic] 15.
Apparatuses and processes of the type stated initially are already known. In the case of traditional systems of this type, metal plates, in particular imprinted and/or lacquered, running in tandem are introduced into a stacking device, by way of example formed as a stack box, and there are stacked lying on one another. Therein the metal plate feed is accomplished by means of a feed transport device connected at the front in relation to the stacking device, by way of example in the form of a feed belt transport device, which is preferably operated at a constant rate. The metal plates are conveyed horizontally into the stacking device (stack box), braked after the last path section by means of a fixed stop absorption system, and finally stored in the stacking device. Therein the metal plates describe, on running into the stacking device, a flight path wherein the front metal plate corners incline more or less toward dipping. Dipping of this type, in particular in the case of metal plates with so-called “scroll plate sections,” is so pronounced that the relatively unstable corners swing through very sharply downwards. Such undesired swinging motions of a current metal plate can lead to the front plate corner of a metal plate reaching the stacking device dipping into the section gap of a metal plate already lying (stored) in the stacking device and interlocking with its edges. This leads to a disturbance of the stack in the device, said disturbance to be avoided as a matter of principle and frequently causing a complete running into one another of the metal plates and thus possibly leading to the entire production line coming to a standstill.
It is the objective of the invention to provide an apparatus and a process of the type stated initially by means of which a disturbance-free and correct transporting and stacking of goods, in particular in the form of plates, is possible, preferably with a relatively high throughput of goods (number of transported and stacked goods per unit of time).
The objective is realized by an apparatus with the features of claim 1. The apparatus is characterized by an overhead transport device which is disposed at least partially in a stacking area above the stacking device and which has a holding system which can be activated and deactivated, where a delay system is provided for time-delayed activation of an effective holding force of the overhead transport device at a point in time when a front, seen in the direction of transport, area of the goods overlaps the stacking area in the direction of stacking. In addition the overhead transport device serves in particular for braking the current goods essentially up to a standstill in a stacking mode position (transport velocity zero or nearly zero) and for the subsequent stacking of the goods in the stacking device, in particular by free fall (stacking direction) of the same. Since the goods (for example, metal plates) then fall downwards essentially perpendicularly in the stacking device, practically no horizontal relative motion of each metal plate to be stacked takes place during the actual stacking process so that no undesired interlocking of metal plates having so-called “scroll comers” can occur in the stacking device. The braking of a current metal plate can then be done controlled by means of the holding system of the overhead transport device and not, as in the state of the art, by means of a fixed stop absorption system in which the horizontal kinetic energy of a metal plate is exhausted by a substantially frontal, elastic impact.
Damage of metal plates to be disposed lying on one another can then be avoided in a reliable manner since the metal plate currently to be stacked in the stacking device is not moved along a flight path with horizontal component but rather storing of the same is accomplished in the form of a free fall essentially purely in the vertically direction. In this manner relative motions between two metal plates lying on one another and thus corresponding surface damage as a consequence of friction are avoided. Moreover, the metal plate currently to be stacked is not exposed to a sudden force of impact in the horizontal direction (stop) which in particular can cause damage to the edges of the metal plate. Advantageously, alignment movements of a current metal plate in the stacking device, such as, for example, in the form of a pushing back of a currently upper metal plate in the stacking device, can be omitted since the metal plates are always positioned in a definite stacking mode position by means of the holding system of the overhead transport device before its free, vertical fall in the stacking device. Thus, horizontal relative movements between metal plates already lying on one another in the stacking device (alignment movements) can also be avoided. The apparatus according to the invention thus makes it possible to separate horizontal movement phases from vertical movement phases in such a way that no horizontal relative movement between two metal plates in contact can arise and thus also no danger of interlocking and/or danger of scratching on the surfaces of the same. In given cases, the feed transport device can be formed as an overhead transport device so that merely a single transport device is provided. Furthermore, a large throughput of goods through the apparatus and thus a rapid stacking of the same goods is made possible since the delay time period is utilized for the transport of goods as well as for bridging the necessary activation time of an effective holding force in the overhead transport device.
Advantageously the holding system is adjustable in its velocity. Thereby it is possible that the kinetic energy of a current metal plate can then be completely exhausted merely by motor by means of a, by way of example electromotive, braking system, where the corresponding metal plate can still be located in an extended run-in plane of the stacking device. Here “adjustable in its velocity” is understood to mean that the holding system, by way of example, can be set variably by means of a control unit to different operating velocities. The operating velocities can each be changeable as a constant, continuously, or discontinuously. The delay time period can thus be utilized for the transport of goods as well as for the simultaneous acceleration of the holding system (for example, in the form of an overhead transport device) to a predetermined operating velocity so that also thereby a greater throughput through the apparatus and thus a more rapid stacking of the same goods is made possible.
Advantageously the holding system has at least one overhead belt, which is coupled to a vacuum and/or magnetic system to form a, in particular, variable holding force. In this case the overhead belts are provided with holes by use of a vacuum system. By means of a holding system of this type holding forces can be generated which act upwards through the overhead belt and thus make possible reliable adhesion of the goods (metal plates) to the overhead belt. In so doing it is possible that the current goods reproduce the exact movement of the overhead belt free of relative movements until on deactivation of the vacuum and/or magnetic system a free fall in the vertical direction of the goods located in the stacking mode position in the stacking device occurs. To guarantee an optimal holding of the plate by means of the holding system, preferably four overhead belts spaced at a distance from one another are provided. The number and/or arrangement of the overhead belts depends, in particular, on the size and geometric form of the goods.
According to a possible form of embodiment the feed transport device is formed below the goods to be transported, and in particular as a belt transport device. A feed transport device of this type preferably extends in the horizontal direction and is particularly suited to reliable and rapid feeding of goods, such as, for example, metal plates in the stacking device. In addition the feed transport device can also have a plurality of transport belts, where the arrangement of the transport belts is intended to be adapted to the feed transport device so that an overlapping arrangement of the overhead transport device and the feed transport device is possible.
The overhead transport device preferably has a holding force area whose front, seen in the direction of transport, end lies in the stacking area. Thus the zone of the holding forces of the holding system (vacuum and/or magnetic system) only begins in the area above the stacking device (stack box), preferably several centimeters removed from the stacking device. In the case of overlapping overhead belts and feed belts lying below in front of, seen in the direction of transport, the stacking device, no upwardly directed holding forces are therefore acting on the overhead belt or belts. In this way the (current) overhead belt can be still be influenced with regard to its transport velocity (acceleration phase) while the goods (metal plate) carried by the (current) feed belt and moving in the direction of the overhead belt have still not reached with their front edge the zone of the holding forces of the holding system of the overhead transport device. Thus a fixing of the current goods to the overhead transport device is done at a relatively late point in time.
The holding force area of the overhead transport device and the feed transport device can be disposed at a distance from one another, seen in the direction of transport. In this case the feed transport preferably ends in front of the stacking device. At the same time the feed transport device and the overhead transport device can be disposed overlapping one another, seen in the direction of transport, with the formation of an, in particular, essentially horizontal transport gap. By means of an apparatus of this type it is possible to guarantee reliable transport of goods with correct transfer of the same from the feed transport device to the overhead transport device, where the holding force area of the holding system of the overhead transport device begins relatively toward the back, seen in the direction of transport, that is, in the stacking area of the goods above the stacking device.
According to a possible form of embodiment, the overhead transport device has, in relation to the direction of transport of the feed transport device, an inclined transport surface. In this case the transport surface of the overhead transport device is preferably inclined in relation to the horizontal (horizontal direction of transport of the feed transport device) where the angle of inclination is, in particular, circa 2° to 5°. Thereby it is made possible that the current goods (for example, a metal plate) on beginning running in into the stacking device project freely over the feed transport device and contact the overhead transport device with slight force due to a possible front edge movement without, however, striking the same or a noteworthy deflection of the direction of transport taking place. The transport gap tapering due to the slight inclination of the overhead transport device in the direction of transport causes a gradual approach of the front, seen in the direction of transport, area of the goods to the overhead belt or belts. Thereby a reliable fixing of the current goods on the overhead transport device is guaranteed. This is to be traced back to the fact that the holding forces in the vicinity of the overhead transport device (overhead belt) are disproportionately reduced by the distance of the current goods from the overhead belt. Through the approach of the goods to the overhead belt due to the inclination of the overhead transport device it is prevented that the goods arrive in an area of low holding forces (too great a distance from the overhead belt) and threaten to fall off of the overhead transport device. At the same time the inclination can be kept so small that no negative impact effects due to a negligible change in the direction of transport of the goods can set in.
Preferably the feed transport device and the overhead transport device with regard to their transport surfaces are spaced relative to one another essentially perpendicular to the direction of transport, in particular with a spacing of circa 1 mm to 10 mm. A spacing of this type guarantees an impact-free transfer of a goods (for example, metal plate) from the feed transport device to the overhead transport device.
Advantageously the magnetic system has at least one electromagnet working according to the principle of flux expulsion which on its activation is suitable for the compensation of a magnetic field of at least one permanent magnet. By means of a magnetic system of this type relatively short turn-on and turn-off times (activation and deactivation of the electromagnet) can be achieved. By so doing, current is applied to the electromagnets merely for a relatively brief moment so that ON-period operation is possible. This promotes a very compact construction of the electromagnets. A further advantage consists of the low thermal load of the electromagnets associated with this and the relatively long lifetime of the same resulting from it. By means of a magnetic system of this type a reliable and precisely timed activation and deactivation of the holding system is thus possible.
Preferably a sensor unit is provided for sensing at least one definite transport position of the current goods. The sensor unit can, by way of example, consist of two sensors lying opposite one another for recognition of the back edge of a current metal plate (goods). In this case the signals of the sensor unit are, in particular, important for the precisely timed activation and deactivation of the holding system of the overhead transport device as well as for the corresponding acceleration and braking of the overhead belts of the same.
According to a preferred form of embodiment a central control or regulatory device is provided for setting of the operational parameters of the holding system of the overhead transport device, in particular of the braking and acceleration parameters as well as for the activation and deactivation of the holding system as a function of the transport parameters of the feed transport device and/or of the dimensions of the goods, in particular exploiting the information from the sensor unit. A control or regulatory device of this type serves for the automatic and correct operation of the apparatus.
Advantageously the overhead transport device and/or the stacking device are adjustable in width and/or length and/or height for the adaptation to, in given cases, different format sizes of the goods. Thus goods of the most varied forms and format sizes can be transported and stacked by means of the apparatus.
Advantageously the stacking device has at least one guide wall for the edge of the goods provided with, in particular, a plurality of air outlet openings. Thereby the free fall in the vertical direction of the goods (for example, metal plate) is accelerated in the stacking direction since no air cushion which is too large can build up under the falling goods (particularly important in the case of rectangular plates). In particular, the front and back guide walls for the edge of the goods in the stacking device (for example, stack box) are provided with suitably large air outlet openings.
For the realization of the objective a process for transporting and stacking of goods, in particular in the form of a plate, is furthermore proposed, said process having the features of claim [sic] 15. The process is characterized by the fact that the current goods are transported by means of an overhead transport device into a stacking area in which it is brought essentially to a standstill and subsequently released from the overhead transport device for the stacking of the goods in the stacking device, in particular by free fall of the same, where a time-delayed activation of an effective holding force of the overhead transport device occurs at the point in time when a front, seen in the direction of transport, area of the goods overlaps the stacking area in the direction of stacking. By means of a process of this type the aforementioned advantages in relation to the apparatus can be achieved.
Preferably the process is characterized by the following processing steps:                conveying the current goods from the feed transport device to the overhead transport device disposed at least partially in the stacking area above the stacking device,        acceleration of a holding system of the overhead transport device essentially to the feed velocity of the goods,        activation of the holding system for fixing the goods in a holding force area of the overhead transport device,        braking of the holding system with the goods until it comes to a standstill in the stacking area,        deactivation of the holding system for stacking of the goods during the free fall setting in essentially in the vertical direction in the stacking device.        
In so doing the feed velocity of the goods achievable by means of the feed transport device is preferably adjustable and constant. A process of this type permits a particularly gentle stacking of goods, such as, for example, of thin metal plates, and at the same time, in given cases, the setting of relatively high transport velocities since by means of the holding system the current goods are braked to a velocity of zero and thus in contradistinction to traditional processes no stopping of the current goods on absorption element has to be done, which could lead to undesired damage to the goods, such as, for example, a front edge of a plate. Furthermore, it is not necessary to provided a stacking fan to influence the “free flight path” of the current goods as is necessary in the case of conventional stacking processes.
According to a preferred embodiment variant the activation of the holding system occurs after reaching a transport surface of the overhead transport device in the holding area by means of the front area of the goods and, in particular, after producing a surface contact of the front area with the transport surface. In this case the holding force area lies preferably within the stacking area of the goods above the stacking device. This make possible a relatively “late” engagement of the holding forces by means of activation of the holding system, preferably when the feed velocity of the goods and the overhead belt velocity are equal.
Preferably a change in the direction of transport of circa 2° to 5° relative to the direction of transport of the feed transport device, and, in particular with regard to the horizontal, occurs during the conveyance of the goods from the feed transport device to the overhead transport device to promote a surface contact of the goods on a transport surface of the overhead transport device by means of the same. Due to the change in the direction of transport, the goods (for example, metal plate) fall vertically in a correspondingly inclined position in the stacking device onto, in given cases, already stacked goods. Also thereby an undesired formation of a relatively large air cushion between the free-falling goods and the stack lying under them can be avoided or at least limited.
Advantageously a back edge of the goods is sensed in a definite transport position by means of a sensor unit for subsequent successive triggering of the activation, the braking, the deactivation, and the acceleration of the holding system. Thus the braking program including the braking process, the turning off of the electromagnets, the restarting of the overhead belts, and turning on of the electromagnets once again is started by means of a back edge pulse. With a front edge sensor a secure execution of the braking process would only be possible indirectly since a light scanner and not a one-way light barrier would have to be used. Furthermore, with the use of a front edge sensor the control would have to recognize the length format of the goods or the front edge sensor would have to be displaceable, whereby an additional operational setting would be necessary.
Advantageously the activation of the holding system is done as a function of sensing of a definite transport position of the goods after a constant, in particular, determinable time period has elapsed. Thus a constant “deadtime” between a sensory recognition of a current goods and a later successful, actual turning on of the holding system is adhered to. This has as a consequence that the goods at a higher transport velocity have already reserved a larger transport path before the turning on of the holding forces by means of the activation of the holding system occurs so that the actual turning of the holding forces at higher velocities in relation to the transport path reserved occurs later.
According to an alternative embodiment variant the point in time of the activation of the holding system is defined as a function of transport velocity of the feed transport device and/or the material and/or the geometric formation of the goods. Thereby a flexible fixing of the current goods on the overhead transport device by means of the holding system is possible.
By means of the control or regulatory device, in particular utilizing a parameter-dependent code field, automatic transporting and stacking of the goods can be done. By way of example, in the case of goods in the form of a plate, the point in time of activation of the holding system can be made a function of the plate material present (for example aluminum/steel), the wall thickness (thin/thick), the plate length and/or width, and the like by means of a parameter-dependent code field. A code field of this type is, in particular, velocity-dependent so that, with increasing transport velocity, the point in time of activation of the holding system is realized accordingly later.
Further advantageous developments of the invention follow from the description.